Quantifying the lateral lipid domain properties in erythrocyte ghost membranes using EPR-spectra decomposition

Using EPR spectroscopy a typical lateral domain structure was detected in the membranes of spin-labeled bovine erythrocyte ghosts. The spectral parameters were determined by decomposing the EPR spectrum into three spectral components and tuned by a hybrid-evolutionary-optimization method. In our experiments the lateral domain structure and its properties were influenced by the variation in the temperature and by the addition of n-butanol. The specific responses of the particular domain types were detected. For the most-ordered domain type a break was seen in the temperature dependence of its order parameter, while the order parameters of the two less-ordered domain types exhibited a continuous decrease. Below the break-point temperature the alcohol-induced membrane fluidity variation is mainly a consequence of the change in the proportions of the least- and the most-ordered domain type and not the change of the domain-type ordering or dynamics (with n-butanol concentration). On the other hand, the fluidity variation above the break-point temperature arises from both types of changes. Interestingly, the proportion of the domain type that has its order parameter between that of the least- and the most-ordered domain type remains almost constant with concentration as well as with temperature, which implies its stability. Such characterization of the lateral membrane domain structure could be beneficial when considering the lipid-protein interactions, because it can be assumed that the activity of the membrane-bound enzyme depends on the properties of the particular domain type.     

Bifurcation of periodic solutions to variational inequalities in R κ based on Alexander-Yorke theorem

Variational inequalities are studied, where K is a closed convex cone in , 3, B is a × matrix, G is a small perturbation, a real parameter. The assumptions guaranteeing a Hopf bifurcation at some ₀ for the corresponding equation are considered and it is proved that then, in some situations, also a bifurcation of periodic solutions to our inequality occurs at some _{I 0}. Bifurcating solutions are obtained by the limiting process along branches of solutions to penalty problems starting at ₀ constructed on the basis of the Alexander-Yorke theorem as global bifurcation branches of a certain enlarged system.     

Next nearest neighbor effect in chromite

In this paper the Mossbauer spectra of a chromite at 140K 200K and 298K were measured. Next nearest neighbor effects were used to explain the spectra of the chromite, and multiple doublets of Fe²⁺ ions on the A sites were caused by the different cation combinations on 12 next nearest neighbor B sites. The quandrupole splitting of each of mult iple Fe²⁺ doublets decreases with increasing temperature.     

Electrical resistance of platinum wires during annealing and quenching in air and helium

Electrical resistance of platinum wires annealed and quenched in air and helium was measured. No irreversible changes of the electrical resistance were observed in specimens treated in helium, however, these changes were appreciable in specimens treated in air. By measurement at two temperatures the total change was divided into the change of the electrical resistivity and the change of geometrical dimensions. The changes of geometrical dimensions were interpreted in terms of the oxidation of platinum and the activation energy of oxidation of platinum was determined asE=(1.79±0.04) eV.     

Ion exchangers containing phosphorus in their functional group

Summary Uranium or thorium separations from a number of various ions were studied by means of cation exchangers containing phosphorus in their functional group. These ion exchangers adsorb selectively only UO₂ ²⁺ or Th⁴⁺ ions from the mixture studied in a medium of >0.4 N nitric or hydrochloric acid. Several di- and trivalent cations are not sorbed under these conditions. In the absence of UO₂ ²⁺ and Th⁴⁺ ions, Me²⁺ may be more easily separated quantitatively from Me³⁺ in 0.2 N nitric or hydrochloric acid than with cation exchangers containing the -SO₃H group.

---

Zusammenfassung Die quantitative Trennung von UO₂ ²⁺ oder Th⁴⁺ von einer Reihe anderer Ionen wurde mit Hilfe phosphorhaltiger Kationenaustauscher untersucht. Diese Ionenaustauscher sorbieren selektiv nur UO₂ ²⁺ oder Th⁴⁺-Ionen aus einem Medium von >0,4 N HNO₃ oder HCl. Eine Reihe verschiedener zwei- und dreiwertiger Kationen wird unter diesen Bedingungen nicht sortiert. Bei Abwesenheit von UO₂ ²⁺- und Th⁴⁺-Ionen kann man Me²⁺ in 0,2 N HNO₃- oder HCl-Lösung quantitativ von Me³⁺ trennen, und zwar leichter als mit -SO₃H-haltigen Austauschern.

     

Coulometrische permanganatometrische bestimmung von wasserstoffperoxyd

A method has been developed for the quantitative coulometric permanganatometric micro-determination of hydrogen peroxide. The end-point is ascertained by the colour changes of the indicators ferroin, and nitro-ferroin respectively